基于eDNA技术的长江上游三峡变动回水区春季鱼类多样性研究

Spring fish diversity in fluctuating backwater zone of Three Gorges Reservoir, Upper Yangtze River using eDNA metabarcoding

摘要

【目的】三峡变动回水区鱼类资源的持续动态监测对评估保护措施成效、制定针对性管理策略具有重要意义。在长江十年禁渔的背景下,非侵入式eDNA技术为获取鱼类资源信息提供了一种高效且便捷的途径。【方法】选取长江上游三峡变动回水区广阳坝河段为研究区域,采用eDNA技术对三峡变动回水区内鱼类多样性进行调查,分析三峡变动回水区的鱼类群落组成,评估三峡变动回水区内鱼类种类,为三峡变动回水区鱼类多样性保护提供数据支撑。【结果】eDNA技术共检测出63种鱼类,隶属5目10科48属,其中鲤形目最多,占比73%;相对序列丰度分布较大的种类有鲤(Cyprinus carpio)、鳙(Hypophthalmichthys nobilis)、汪氏近红鲌(Ancherythroculter wangi)、草鱼(Ctenopharyngodon idella),驱动鱼类群落空间分布格局的关键环境因子为流速和电导率;长江上游变动回水区广阳坝河段鱼类α多样性差异不大,Shannon多样性指数平均值为1.67,Simpson多样性指数平均值为0.63,不同样点间的物种β多样性主要受其周转组分主导;长江上游变动回水区广阳坝河段定居型喜缓流生境的鱼类占比较大,产沉性卵的鱼类占据主要地位。【结论】三峡变动回水区广阳坝河段鱼类群落结构正在由河流生态系统向河库型生态系统重新分布,喜急流的长江上游珍稀特有鱼类栖息地逐渐向上游国家级珍稀特有鱼类保护区移动。

Abstract

[Objective] Continuous dynamic monitoring of fish resources in the fluctuating backwater zone of the Three Gorges Reservoir is essential for evaluating the effectiveness of conservation measures and for formulating targeted management strategies. Against the backdrop of the 10-year fishing moratorium on the Yangtze River, non-invasive environmental DNA(e DNA) metabarcoding offers an efficient and convenient means of acquiring information on fish assemblages. [Methods] The Guangyangba section in the fluctuating backwater area of the Three Gorges Reservoir, the Upper Yangtze River was selected as the study area. The e DNA metabarcoding was employed to investigate fish diversity within the fluctuating backwater zone of the Three Gorges Reservoir, analyze the fish community composition, and assess fish species within the area, thereby providing data support for conservation of fish diversity in the fluctuating backwater zone. [Results] A total of 63 fish species were detected by e DNA metabarcoding, belonging to 5 orders, 10 families, and 48 genera, with Cypriniformes being the most abundant, accounting for 73 % of all records. The species with relatively high relative sequence abundance included Cyprinus carpio(common carp), Hypophthalmichthys nobilis(bighead carp), Ancherythroculter wangi, and Ctenopharyngodon idella(grass carp). Key environmental factors driving the spatial distribution patterns of fish communities were identified as flow velocity and conductivity. α-diversity among fish in the Guangyangba section of the fluctuating backwater zone in the Upper Yangtze River exhibited minimal variation, with an average Shannon diversity index of 1. 67 and an average Simpson diversity index of 0. 63. β-diversity among different sampling sites was governed primarily by turnover components. Resident species favouring slow-flow habitats and those producing demersal eggs dominated the Guangyangba section. [Conclusion] The fish community structure in the fluctuating backwater zone of the Three Gorges Reservoir is undergoing a redistribution from a riverine to a river-reservoir ecosystem, with habitats preferred by rheophilic, rare, and endemic fish species of the Upper Yangtze River progressively shifting upstream towards the national nature reserve for rare and endemic fish species.

关键词

环境DNA / 长江上游变动回水区 / 鱼类群落 / 多样性 / 生态类群 / 环境因子 / 保护策略 / 影响因素

Key words

environmental DNA / fluctuating backwater zone of Upper Yangtze River / fish community / diversity / ecological guild / environmental factors / conservation strategies / influence factors

基金资助

国家自然科学基金(42007213)

重庆市自然科学基金创新发展联合基金项目(CSTB2023NSCQ-LZX0157)